Elucidating effects of cell architecture, electrode material, and solution composition on overpotentials in redox flow batteries

An improved method for quantitative measurement of the charge transfer, finite diffusion, and ohmic overpotentials in redox flow batteries using electrochemical impedance spectroscopy is presented. The use of a pulse dampener in the hydraulic circuit enables the collection of impedance spectra at lo...

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Bibliographic Details
Published in:Electrochimica acta 2017-03, Vol.229 (C), p.261-270
Main Authors: Pezeshki, Alan M., Sacci, Robert L., Delnick, Frank M., Aaron, Douglas S., Mench, Matthew M.
Format: Article
Language:English
Subjects:
Batteries
Carbon
catalysis (heterogeneous), solar (fuels), energy storage (including batteries and capacitors), hydrogen and fuel cells, electrodes - solar, mechanical behavior, charge transport, materials and chemistry by design, synthesis (novel materials)
Charge transfer
Composition effects
Concentration (composition)
Diffusion
Diffusion pumps
Diffusion rate
Electrochemical impedance spectroscopy
Electrodes
finite diffusion resistance
impedance-resolved polarization
Low frequencies
rate constant
Rechargeable batteries
redox flow battery
Vanadium
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Summary:An improved method for quantitative measurement of the charge transfer, finite diffusion, and ohmic overpotentials in redox flow batteries using electrochemical impedance spectroscopy is presented. The use of a pulse dampener in the hydraulic circuit enables the collection of impedance spectra at low frequencies with a peristaltic pump, allowing the measurement of finite diffusion resistances at operationally relevant flow rates. This method is used to resolve the rate-limiting processes for the V2+/V3+ redox couple on carbon felt and carbon paper electrodes in the vanadium redox flow battery. Carbon felt was limited by both charge transfer and ohmic resistance, while carbon paper was limited by charge transfer, finite diffusion, and ohmic resistances. The influences of vanadium concentration and flow field design also are quantified.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2017.01.056